Chicken Kosha (চিকেন কষা)

A Bengali Comfort Classic

Chicken Kosha is a classic Bengali chicken curry where the focus is not just on ingredients but on the slow koshano (bhuna) process. The chicken is gradually cooked with onions, spices and mustard oil until the masala thickens, darkens and clings beautifully to every piece, creating the signature rich texture and flavour.

• Prep Time: 30 mins
• Cook Time: 1 hr 15 mins
• Serves: 6

Ingredients

• 1250 g bone-in chicken
• 3 tbsp sour curd
• 1 tsp turmeric powder
• Salt to taste
• 8 tbsp mustard oil
• 5 large onions, finely chopped
• 1.5 tbsp ginger paste
• 2 tbsp garlic paste
• 1.5 tomatoes, finely chopped (optional)
• 2-3 green chillies, slit
• 2 bay leaves
• 3-4 pieces cinnamon
• 3 green cardamoms
• 4 cloves
• 1 tsp turmeric powder
• 1 tsp red chilli powder
• 1.5 tsp Kashmiri chilli powder
• 2 tsp coriander powder
• 1/2 tsp garam masala
• 1/2 tsp sugar
• Water as required

Method

1. Marinate chicken with curd, turmeric powder and salt for 30 minutes
2. Heat mustard oil until smoking, then reduce the flame slightly
3. Add bay leaves, cinnamon, cardamom and cloves
4. Add chopped onions and a pinch of salt, then cook on medium-low heat until deep golden and slightly sticky
5. Add ginger paste and garlic paste, cook until the raw smell disappears
6. Add chopped tomatoes if using, add a little sugar and cover for 5 minutes until softened
7. Mix all powdered spices with a little water and add to the kadai
8. Cook until the masala becomes smooth, thick and starts releasing oil
9. Add the marinated chicken and bhuna on high flame until the chicken turns slightly pale and firms up
10. Lower the flame and continue the koshano process by cooking, scraping and adding small splashes of water repeatedly 4-5 times
11. Add green chillies
12. Continue cooking until the masala darkens, coats the chicken and releases light oil
13. Cover and cook until the chicken is fully done
14. Remove the lid and do a final bhuna
15. Add garam masala and sugar
16. Rest for 5-10 minutes before serving

Chef’s Tips

• The onion stage is critical; cook slowly until deep golden and sticky
• Always cook powdered spices with a little water to prevent burning
• Add only small splashes of water during bhuna
• The koshano process creates the signature texture, not simply reducing gravy
• A good kosha should have masala clinging to the chicken with slight oil release but not be overly oily

Frequently Asked Questions

• Can I skip the tomato? Yes, increase the curd slightly and the recipe will still work
• Why mix spices with water before adding? It prevents burning and helps flavours develop smoothly
• Why is my kosha turning into jhol? Too much water during bhuna can loosen the gravy
• Can I make it ahead? Yes, the flavour improves after a few hours of resting